The present invention relates to a nonvolatile semiconductor memory device and especially, to a nonvolatile memory device with wired-OR structure and an associated driving method.
Programming or reading data from memory cells in a nonvolatile semiconductor memory device typically requires controlling a bitline voltage corresponding to a selected memory cell. For controlling the bitline, the nonvolatile memory device embeds a page buffer to store the read out and/or program data bit.
FIG. 1 is a block diagram of a conventional nonvolatile memory device including a page buffer PBF. FIG. 2 illustrates a column gate YG (one of YG<1>˜YG<n>) corresponding to one of page buffers PBP (one of PBP<1>˜PBP<n>) shown in FIG. 1. In the conventional page buffer PBP, a data bit written into a memory cell is loaded and stored in a sensing/latching block 150. The data bit held in the sensing/latching block 150 is transferred to a bitline BLe or BLo and programmed in a selected memory cell. A data bit corresponding to a data bit read out from a memory cell is also temporarily stored in the sensing/latching block 150. Responding to one of the column gating signals Ya<n:1>, the stored data bit stored is transferred to a global data line GDL.
In the conventional nonvolatile memory device, as shown in FIGS. 1 and 2, internal data lines IDL of the page buffers PBP are commonly connected to the global data line GDL through their corresponding column gates YG. The data path from the global data line GDL to a sensing/latching node NLATP is commonly used by a data bit during programming and reading operations. Data stored in the sensing/latching node NLATP may flip, change, or otherwise corrupt due to a charge sharing between the global data line GDL and the internal data line IDL.
A program verifying operation for the conventional nonvolatile memory device is conductive in a Y-scanning scheme if it serially or sequentially confirms each of the data bits in programmed memory cells. By contrast, a wired-OR scheme confirms, at one time, all the data bits in programmed memory cells. The conventional nonvolatile memory device therefore has an unnecessarily lengthy program data verifying operation.
Accordingly, a need remains for a non-volatile semiconductor memory device with a load-supplying wired-OR structure and an associated driving method.